Power management utilizing synchronous common coupling

ABSTRACT

Apparatuses, systems, and methods for managing power utilizing synchronous common coupling. An apparatus comprises a synchronous common coupling, a plurality of ports, and a plurality of stacks connected through the synchronous common coupling. Each stack comprises at least one stage, with each stage comprising at least one source/load bridge, at least one flux bridge, and a DC bus. The at least one source/load bridge of one stage of each stack is connected to a source or load through one of the plurality of ports, the at least one flux bridge of each stage is connected to an electrically isolated winding in the synchronous common coupling, and the at least one flux bridge of each stage is connected to the at least one source/load bridge of the stage through the DC bus. The synchronous common coupling is configured to exchange power between each of the plurality of stacks.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.15/705,938, filed Sep. 15, 2017, and entitled “POWER MANAGEMENTUTILIZING SYNCHRONOUS COMMON COUPLING,” which is a continuation of U.S.application Ser. No. 15/285,401, filed Oct. 4, 2016, and issued as U.S.Pat. No. 9,780,682 entitled “POWER MANAGEMENT UTILIZING SYNCHRONOUSCOMMON COUPLING,” which claims the benefit of U.S. ProvisionalApplication No. 62/237,275, filed Oct. 5, 2015, the entire disclosuresof which are hereby incorporated herein by this reference.

BACKGROUND

The energy industry has depended solely on fossil fuels, but it is nowshifting investment to develop new cheaper and cleaner energy sourcesnot related to fossil fuels. Over the past two decades, renewable energyresources have been the focus for researchers, and many different powerconverters have been designed to make the integration of these types ofsystems into a distribution grid. As the power grid evolves, there willbe more distributed power sources that are configured into microgrids.Microgrids operate with both utility (power network) and renewable powersources (solar, wind, battery, and/or other) with numerous various loads(single and three-phase). Medium, high, and extra high voltageelectronic systems are needed to manage and control power flow as wellas to assure power distribution quality in transmission lines such asapplications for reactive power (“VAR”) compensators, voltage/frequencyregulators, solid-state transformers (“SST”), solid-state powersubstations (“SSPS”), medium and high voltage direct current(“MVDC”/“HVDC”) drives, medium voltage alternate current drives (“MVD”),and others. Therefore, power electronic converters with thesecapabilities have the responsibility to carry out these tasks with highresiliency and efficiency. The increase in the world energy demands hasnecessitated the appearance of new power converter topologies and newsemiconductor technology.

Electrical power networks produce and use real/active andimaginary/stored power. Typically, power lines carry active power (“KW”)and reactive power (“VAR”). The content of active and reactive power isexpressed in power factor. As the total power flows through the line,both active and reactive power compete for capacity. VAR compensation isdefined as the management of reactive power to improve the performanceof alternate current (“AC”) power networks. The concept of VARcompensation embraces a wide and diverse field of both system andcustomer problems, especially related with power quality issues, sincemost power quality problems can be attenuated or solved with an adequatecontrol of reactive power. In general, the problem of reactive powercompensation is viewed from two aspects: load compensation and voltagesupport. In load compensation, the objectives are to increase the valueof the network power factor, to balance the real power drawn from the ACsupply, to compensate voltage regulation, and to eliminate currentharmonic components produced by large and fluctuating nonlinearindustrial loads. Voltage support is generally required to reducevoltage fluctuation at a given terminal of a transmission line. Reactivepower compensation in transmission networks also improves the stabilityof the AC network by increasing the maximum active power that can betransmitted. It also helps to minimize variation at all levels of powertransmission, it improves HVDC conversion terminal performance,increases transmission efficiency, controls steady-state and temporaryover-voltages, and can avoid disastrous blackouts. VAR compensatorsystems can be electromechanical or static (“SVC”) and can be series orshunt reactive compensators. Series and shunt VAR compensation are usedto modify the natural electrical characteristics of AC power networks.Series compensation modifies the transmission or distribution networkparameters, while shunt compensation changes the equivalent impedance ofthe load. In both cases, the reactive power that flows through thenetwork can be effectively controlled, improving the performance of theoverall AC power network.

Conventional multi-level cascaded power management systems use a largethree-phase 60 Hz transformer with multiple electrically isolatedthree-phase secondaries which may be phase shifted. These conventionalsystems supply power to electronic assemblies that convert the 60 Hzpower feeding to a variable frequency (0 to 120 Hz) and voltage output.Each output may be implemented with an H-bridge and because theseoutputs are electrically isolated by the large 60 Hz transformer withisolated secondaries, the H-bridges can be connected in series orparallel. However, there is a need for more efficient systems over theseexisting Cascaded H-Bridge (“CHB”) topology.

CHB solutions are costly, complex, and unreliable because the designsare limited in switching frequency, dielectric, and thermal capabilityas well as requiring complicated hardware and cable assemblies.Traditionally, utilities avoid power electronic products due to cost,complexity, and lack of resiliency. In addition, these power electronicproducts require extra cost for installation because they are designedfor operating in clean controlled environments. Within industry, manylarge motor applications would benefit from using power factorcorrection on constant speed motors, to save energy through VAR support,but most motor applications do not use power electronic solutions due tocost and reliability concerns. Due to renewable energy and the need forgreater network resiliency, new electrical networks are emerging withmultiple distributed energy sources rather than few large sources. Theneed for more flexible and efficient power flow control within amulti-source environment is well documented.

It is with respect to these and other considerations that the disclosuremade herein is presented.

SUMMARY

It is to be understood that this summary is not an extensive overview ofthe disclosure. This summary is exemplary and not restrictive, and it isintended to neither identify key or critical elements of the disclosurenor delineate the scope thereof. The sole purpose of this summary is toexplain and exemplify certain concepts of the disclosure as anintroduction to the following complete and extensive detaileddescription.

According to some aspects, an exemplary power management apparatusutilizing synchronous common coupling comprises a synchronous commoncoupling, a plurality of ports, and a plurality of stacks connectedthrough the synchronous common coupling. Each stack comprises at leastone stage, with each stage comprising at least one source/load bridge,at least one flux bridge, and a DC bus. The at least one source/loadbridge of one stage of each stack is connected to a source or loadthrough one of the plurality of ports, the at least one flux bridge ofeach stage is connected to an electrically isolated winding in thesynchronous common coupling, and the at least one flux bridge of eachstage is connected to the at least one source/load bridge of the stagethrough the DC bus. The synchronous common coupling is configured toexchange power between each of the plurality of stacks.

According to further aspects, an exemplary power management systemutilizing synchronous common coupling comprises a plurality ofsource/load port; a stack connected to each source load port, and acentral controller. Each stack comprises at least one stage, with eachstage comprising a DC bus, at least one flux bridge, and a stagecontroller. The flux bridge of each stage is connected to anelectrically isolated winding in the synchronous common coupling and thestage controller is configured to switch the at least one flux bridge ina synchronized fashion so that power flows from the DC bus of each stackto the connected electrically isolated winding in the synchronous commoncoupling in phase and at the same frequency. The synchronous commoncoupling is configured to exchange power between the stacks, and thecentral controller is configured to control and synchronize the stagecontrollers of each stage.

According to further aspects, a method of utilizing synchronous commoncoupling for power management comprises connecting a power source to afirst source/load port of a power management system, the powermanagement system comprising a plurality of stacks. Each of the stackscomprises at least one stage, each stage comprising at least onesource/load bridge, a DC bus, at least one flux bridge, and controlcircuitry. A first stack of the plurality of stacks is connected to thefirst source/load port, with the source/load bridge of the first stagein the stack connected between the first source/load port and the DCbus, and the flux bridges of the stage connected between the DC bus andelectrically isolated windings of the synchronous common coupling.Control circuitry is utilized to control the flow of power between thefirst source/load port and the synchronous common coupling by switchingthe source/load bridge to synchronize power between the firstsource/load port and the DC bus and switching the flux bridge(s) tosynchronize power between the DC bus and the electrically isolatedwindings of the synchronous common coupling. The synchronous commoncoupling is configured to exchange power between the plurality ofstacks.

These and other features and aspects of the various aspects will becomeapparent upon reading the following Detailed Description and reviewingthe accompanying drawings. Furthermore, other examples are described inthe present disclosure. It should be understood that the features of thedisclosed examples can be combined in various combinations. It shouldalso be understood that certain features can be omitted while otherfeatures can be added.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following Detailed Description, references are made to theaccompanying drawings that form a part hereof, and that show, by way ofillustration, specific embodiments or examples. Any illustratedconnection pathways in block and/or circuit diagrams are provided forpurposes of illustration and not of limitation, and some componentsand/or interconnections may be omitted for purposes of clarity. Thedrawings herein are not drawn to scale. Like numerals represent likeelements throughout the several figures.

FIG. 1 depicts a block diagram of a multi-level cascaded powerconversion circuit, according to prior art.

FIG. 2 depicts a block diagram for a theoretical CHB topology where lineand load are in phase, according to aspects of the present disclosure.

FIG. 3 depicts a block diagram for a theoretical CHB topology utilizinga common DC Bus, according to aspects of the present disclosure.

FIG. 4 depicts a block diagram illustrating a cascaded multi-level andmulti-port power management system with synchronous common couplingusing a single core as the coupling path, according to aspects of thepresent disclosure.

FIG. 5 depicts a block diagram illustrating a stage circuit assemblyincluding a stage connected to a source or load, according to variousaspects of the present disclosure.

FIG. 6 depicts a block diagram illustrating a cascaded multi-level andmulti-port power management system with synchronous common couplingusing multiple high-frequency transformers as the coupling path,according to various aspects of the present disclosure.

FIG. 7 depicts a block diagram illustrating a multi-level and multi-portcascaded power management system with common flux coupling utilizing a3-port array, according to various aspects of the present disclosure.

FIG. 8 depicts a block diagram illustrating one embodiment of a cascadedmulti-level and multi-port power management system with synchronouscommon coupling in a power module, according to various aspects of thepresent disclosure.

FIG. 9 depicts a block diagram illustrating one embodiment of a cascadedmulti-level and multi-port power management system with synchronouscommon coupling in a power module, according to aspects of the presentdisclosure.

FIG. 10 depicts a block diagram illustrating one embodiment of acascaded multi-level and multi-port power management system withsynchronous common coupling with a high-frequency pre-charge and powersupply assembly connected to a power module, according to aspects of thepresent disclosure.

FIG. 11 is a block diagram illustrating a stage circuit assemblyincluding a stage connected to a source or load comprising a singlesource/load bridge coupled to multiple flux bridges through one or moreDC busses, according to various aspects of the present disclosure.

FIG. 12 is a block diagram illustrating a stage circuit assemblyincluding a stage connected to a source or load comprising multiplesource/load bridges coupled to multiple flux bridges through one or moreDC busses, according to various aspects of the present disclosure.

FIG. 13 is a block diagram illustrating a stage circuit assemblyincluding a stage connected to a DC source or load comprising a nosource/load bridge but one or more flux bridges connected to thesynchronous common coupling, according to various aspects of the presentdisclosure.

FIG. 14 is a block diagram illustrating a cascaded multi-level andmulti-port power management system with high-frequency, multiphaseoutput ports, according to various aspects of the present disclosure.

DETAILED DESCRIPTION

The embodiments described herein are directed to high-frequency powerelectronics, more particularly multi-level and multi-port cascaded powermanagement systems with significant improvement in cost, performance,part count, size, efficiency, and resiliency over existing CHB topology.In some embodiments, synchronous common coupling may be used to link thepower flow between multiple electrically isolated and non-isolatedalternating current/direct current (“AC/DC”) sources and loads toprovide a hub for independent power flow control that is indifferent tovoltage magnitude, frequency, and phase. Each power circuit may beprovided with a synchronous common coupling to other power circuits tobetter control power, while maintaining electrical isolation betweencircuits.

According to embodiments described herein there are at least twodifferent implementations of synchronous common coupling technology thatmay be implemented, single common flux core and high-frequency currentbus. The single common flux core utilizes synchronous common coupling toexchange power directly between electrically isolated and non-isolatedstages. The high-frequency current bus utilizes multiple high-frequencytransformers to create a high-frequency current bus. The objective ofsynchronous common coupling is to instantly link power within bridgecircuits internally to the CHB system while keeping electricalisolation. The bridge circuit may also be referred to herein as a “stagecircuit,” “stage,” or “power circuit.” In a CHB topology system withsynchronous common coupling, each stage behaves much better thanconventional power circuits, acting as if it is powered by a three-phasesource with capacitance contributed by all common stages in the system.In some embodiments, the power flows from one stage to another stagethrough the synchronous common coupling, providing each stage withthree-phase power and energy storage from other stages to reduce thenumber of components and improve power flow efficiency, in order toexchange power within the power management system to support reactivepower compensation and phase current balancing. In some embodiments,synchronous common coupling may be unidirectional and scalable, where aDC source may be coupled to the synchronous common coupling to providemore resiliency for network transients and inertia or stored energy forthe conversion system, such as the cascaded multi-level and multi-portpower management systems as described herein, to provide an internal hubfor independent direct power flow control that is indifferent to voltagemagnitude, frequency, and phase to the electrical network.

According to some embodiments, synchronous common coupling may beaccomplished by synchronously switching (e.g., high-frequencyswitching>10 KHz) a flux H-bridge circuit (also referred to herein as“flux bridge”), giving each stage access to power from other stages,because the synchronous common coupling serves as a node to link powerof the stages together while leaving the stages electrically isolated.Synchronous common coupling allows a standard CHB control method tocontrol the source/load H-bridge to meet various objectives, while theflux bridges lower required capacitance with minimal additional controlcomplexity. Synchronous common coupling assists each stage to meet itsinput requirements by supplementing available power to each stage bysynchronously linking its DC bus to every other linked stage's DC bus.Since the DC bus voltage of each stage is the same value, and each stagereceives a synchronous signal to control its flux bridge, thesynchronous linkage enables power flow according to the couplingimpedance between stages to keep DC bus voltage levels the same valuewithout affecting electrical isolation requirements. The common couplingpower flow capability between stages is determined by the couplingimpedance, i.e. the lower the impedance the higher flow capabilitybetween stages. If resonant or soft switching techniques are used withinthe flux bridges, the impedances between stages may be very low. Thestage control continues to operate its input bridge as required per thealgorithm embedded within for the application, while absorbing ortransmitting power through the synchronous flux bridge and linkage asrequired. Each stage control has on/off cycle control for its DC bus toprovide a means to avoid undervoltage or overvoltage events andintrinsic power sharing.

According to some embodiments each stage may use high volume/low costlow voltage components (typically 1200V but in some cases 600V and1700V), however, nothing prevents the use of higher voltage componentsif there are cost benefits. According to some embodiments, packaging ofcomponents may utilize discrete semiconductors on a printed circuitboard with embedded power circuitry and stage controller to produce thesmall size and low cost. Operating at higher switching frequenciesreduces magnetic component size and improve product performance.Controlling power without creating harmful levels of current and voltageharmonics is provided through digital isolation circuits that have highnoise immunity. In some embodiments, each stage receives a commonsynchronous signal from an isolated source and contains energy storagewithin each stage, where energy is regulated by a stage controllerwithin each stage that sends and receives energy, and periodicallysupplies or receives energy to a large energy network.

According to some embodiments, one or more stages may be connectedtogether in a stack. A stack may be the similar to a controllable highvoltage semiconductor H-bridge, but uses low cost and low voltagediscrete semiconductors rather than expensive higher voltagesemiconductor modules. The stack assemblies are more configurable andfault tolerant as well as having much lower Δv/Δt, stray parasitics,temperature variation capability, and overall higher efficiency thanexisting 3300V, 4500V, 6500V, and 10 kV commercially availablesemiconductor modules. According to some embodiments, a stack may beimplemented with internal gate drive and power supplies so that they canbe controlled by a digital control signal. This enables scalable higherpower density and high-frequency operation with lower harmonics withless cost than other commercially available semiconductor moduleassemblies.

Synchronous common coupling significantly reduces part count and losses.It reduces the number of semiconductors, DC bus capacitance, andtransformer cores, and number of windings. Using synchronous commoncoupling within CHB systems improves flexibility and reduces complexityby providing “true power router” capability. It enables multiple AC/DCcascaded sources and loads to efficiently share instantaneous powerbetween phases, sources, and/or loads, indifferent to respectivemagnitude, frequency, phase, impedance, and other characteristics evenduring transient events. Another benefit of using CHB topology withsynchronous common coupling, as described herein, is that it can beconnected as a shunt or series regulator in various applications. Itpermits simple control strategies, enabling low cost and highefficiency. Synchronous common coupling may also provide advantagesduring commissioning, power up, and diagnostic modes. It can be testedprior to applying high voltage and surge current per switching elementmay be reduced due to power sharing, which also aides in pre-chargingpower circuits.

The embodiments described herein may provide significant advantages overexisting state of the art electromechanical and power electronics powerconversion products across a variety of applications, such as VARcompensation, power factor correction, voltage and frequency regulation,solid-state transformers, solid-state power substations, medium voltageAC drives, medium and high voltage DC transmission, test stands, andothers. The embodiments described herein may be fault tolerant of poornetwork power quality and internal failures due to the many like stagesconnected in series, with each having its own stage controller for powerflow and diagnostics.

The embodiments described herein may be implemented to compete in costand resiliency with conventional products constructed of copper, iron,steel, aluminum, and paper. Systems utilizing embodiments described inthis disclosure may be designed to be installed anywhere a transformeror switchgear is traditionally located. The embodiments described hereinmay be used in low, medium, and high voltage applications that requirepower flow control with galvanic isolation. The simplicity of theembodiments described herein result in reduced cost and higherresiliency, as well as achieving small size and high performance. Inaddition, the power circuits and components described in the embodimentsmay be submersed in high dielectric liquids to remove heat, protect thecircuits from electrical or magnetic harm, and reduce both size andweight reducing overall cost while increasing reliability. Submersionmay enable the components to be densely packaged and may provide betterthermal and electrical properties than air. In medium and high voltageapplications, submersion may enable stages and/or stacks from othersources to occupy adjacent space on a circuit board.

Further, some components used by the embodiments described in thisdisclosure may be implemented with soft switching and DV/DT filtersalong with magnetic and electrostatic shields. Further, some embodimentsmay also be implemented with low parasitic capacitance and inductance toreduce electrical noise interference internally between circuits.

Other examples are described in the present disclosure. It should beunderstood that the features of the disclosed examples can be combinedin various combinations. It should also be understood that certainfeatures can be omitted while other features can be added.

FIG. 1 depicts an example block diagram of a conventional multi-levelcascaded power conversion circuit 100, as is known in the art. Themulti-level cascaded power conversion circuit 100 uses a largethree-phase 60 Hz transformer with multiple electrically isolatedthree-phase secondaries (may be phase shifted) that supply power toelectronic assemblies that convert the 60 Hz power feeding to a variablefrequency (0 to 120 Hz) and voltage output. Each output is an H-bridgeand because these outputs are electrically isolated by the large 60 Hztransformer with isolated secondaries, the H-bridges can be connected inseries or parallel, referred to as a cascaded H-bridge (“CHB”) topology.Some CHB units may operate with bidirectional power flow up to 13.8 KV.

While traditional CHB topology has long been considered by industry as apossible solution three-phase AC solid-state transformer to replacetraditional medium voltage transformers to achieve bi-directional powerflow for multi-level cascaded power conversion, it is often tooexpensive to implement because large 60 Hz transformers withmulti-winding secondaries, as shown in FIG. 1, are very expensive,heavy, and large, and products using them require a lot of customizedassembly.

FIG. 2 depicts a block diagram of one theoretical solution utilizing CHBtopology where line and load are in phase (not intertwined). The path ofthe power for this example embodiment would be: AC1-DC-XFMR-DC-AC2. Themain input power supplying power to AC1 contributes directly in phasewith output power AC2 and all AC2 outputs are connected in series thatare powered by the same main input power and are utilizing separate anddistinct transformers between each bridge circuit.

Another possible solution may comprise a CHB topology where thesecondary H-Bridges are intertwined so that more than one phasecontributes to the power generated on the output. The path of the powerfor this example embodiment would be: AC1-DC-XFMR-DC-AC2. However, inthis version, the main input power supplying power to AC1 contributesdirectly in phase with output power AC2, with each bridge circuit AC2output intertwined with AC2 outputs from other main input power phases.

FIG. 3 depicts a block diagram for another theoretical solutionutilizing CHB topology that uses a common DC Bus. The path of thecurrent for this example embodiment in FIG. 3 would be:AC1-DC-XFMR-DC-CDC-AC2, where one phase of the three-phase main inputpower supplying power to AC1 supplies power to a common DC bus (“CDC”),and for non-electrically isolated loads, common DC bus power is directlyconverted to AC by an output H-Bridge. The path of the current may alsoflow as follows: AC1-DC-XFMR-DC-CDC-DC-XFMR-DC-AC2, where the main inputpower supplying power to AC1 supplies power to a common DC bus, and forelectrically isolated loads/sources, common DC bus power is converted toAC through another electrically isolated bridge circuit.

However, the CHB solutions depicted in FIGS. 2 and 3 suffer from limitedflexibility, high part count, high cost, and high losses and thus havenot been implemented by the industry. An important advantage of CHBtopology is that it operates on a single-phase basis rather thanthree-phase, and this enables H-Bridges to be connected in series.However, the traditional CHB single-phase power input requires more DCbus energy storage than three-phase systems which increases part count,cost, losses, and size. Each bridge circuit only permits power sharingbetween other phases, sources, and loads indirectly on the circuit'sinputs and outputs. This causes for power to flow through more circuitry(semiconductors) before it gets to where it needs to go, increasinglosses and part count.

FIG. 4 is a block diagram illustrating a cascaded multi-level andmulti-port power management system 400 with synchronous common coupling440 using a single common flux core 450 as the coupling path, accordingto some embodiments described herein. In the example embodiment shown inFIG. 4, a 6-port 406A-F (also referred to herein generally as ports 406)cascaded multi-level and multi-port power management system 400 may beimplemented with 6 stacks 420A-F (also referred to herein generally asstacks 420) of multiple (N) stages 430A-N (also referred to hereingenerally as stages 430), with each stack 420A-F connected to arespective port 406A-F. Further, the stacks 420A-F are coupled by asynchronous common coupling 440 using a single common flux core 450 asthe coupling path. In the example embodiment, the stages 430A-430N ofeach stack 420 may be connected in series, with the last stage 430N ofeach stack connected to a neutral electrical connection, or “neutral”424. Each stack neutral 424 may be electrically independent or connectedto one or more other stack neutrals 424 forming a group, and eachneutral 424 or group of neutrals circuits within the power conversionsystem may be electrically floated and/or grounded by means of a solidconductor or one or more external network components such as a resistor,a inductor, or a capacitor.

FIG. 5 is a block diagram illustrating a stage circuit assembly 500,including a typical stage 430, as described herein, connected to asource/load connection 402 and/or an adjacent stage through the stageports 502A-B, according to some embodiments described herein. The stage430 may comprise the following sections: input filter 520, a source/loadbridge 432, DC bus 510, and a flux bridge 434.

The input filter 520 may comprise an inductor/capacitor (“LC”) filtercomprising the electrical components that prevent the stage 430 frominjecting fast Δv/Δt transients into the electrical network, such as acapacitor 522, inductors 524, 526, and transient suppressor 528. Thecapacitor 522 and transient suppressor 528 in combination with thecurrent regulating reactor 404 and inductors 524/526 may preventelectrical network transients from harming the stage 430. According tosome embodiments, the input filter 520 may be combined with a currentregulating reactor 404 (as shown in FIG. 4) to create a filter toprevent voltage and current transients on the incoming power lines orloads from harming the stage 430. The stage 430 may also have a currentfeedback 504 located as shown in FIG. 5, or elsewhere with the stagecircuit assembly 500, to provide feedback for regulating the networkcurrent through the stage. According to some embodiments, every stage430 within a stack 420 may provide current feedback 504. In otherembodiments, only one stage 430 within the stack 420 may provide currentfeedback 504 for the other stages 430 since the current flowing throughall series-connected stages 430 in a stack 420 will be the same value.

The source/load bridge 432 may comprise 2, 4, 6, or other number ofswitching devices that may be switched at high or low frequencies or acombination of both depending on the control strategy to regulate thenetwork current. When high-frequency (>10 KHz) switching strategy isused, then fast silicon IGBTs or metal-oxide-semiconductor field-effecttransistors (“MOSFETs”) or Wide Band Gap MOSFETs may be used dependingon required cost, efficiency, and ratings. When low frequency switching(<1 KHz) is used, then low forward saturation silicon IGBTs are possibleas well as IGBT and IGCT modules. For example, the sources/load bridge432 may comprise four switches devices 530A-D comprising insulated gatebipolar transistors (“IGBTs”) configured in a conventional H-bridgeconfiguration, as shown in FIG. 5. In other embodiments, the switchingdevices may comprise integrated gate commutated thyristors (“IGCTs”),wide band gap (“WBG”) semiconductors, or other solid-state components ina half or full bridge, three-phase, or any other suitable configuration.The source/load bridge 432 may also be referred to herein as the “inputH-bridge” or “output H-bridge.” The source/load bridge 432 is used tobalance power throughout the stage 430 and regulates the DC bus 510voltage while creating a low harmonic current waveform. In furtherembodiments, the DC bus 510 may comprise a DC bus capacitor 508 toprovide a low inductance path for the switches, assist in minimizing DCbus ripple voltage, protect the switches from voltage transients, or thelike. The source/load bridge 432 may provide wide input voltagevariation to provide the regulated DC bus 510.

The source/load bridge 432 uses (for example 1-20 kHz) pulse widthmodulate (“PWM”) switching to reduce current and voltage harmonics. Whenmore than one stage 430 is used, the carrier frequency that generatesthe PWM switching may be phase shifted per each stage to effectivelycreate a higher switching frequency than the actual PWM carrier—the morestages 430A-N used, the higher the effective switching frequency. Thistechnique may improve control and current waveform without penalizingthe efficiency of the source/load bridge 432.

According to embodiments, the power flows from one stage 430 to anotherstage 430 through the synchronous common coupling 440. In someembodiments, this results in each stage 430 being provided withthree-phase power and energy storage from other stages to reduce eachstage requirements for DC bus capacitance. The network current (or powerflow) of the stage 430 may be unidirectionally or bidirectionallycontrolled by the source/load bridge 432, which uses one or more currentregulating reactors per source or load to regulate network current orpower flow by switching at least one source/load bridge 432 on/off. Insome embodiments, if the DC bus 510 of the stage 430 does not haveenough power to satisfy the network's current demands, then the DC bus510 voltage begins to drop. However as the DC bus 510 voltage drops,other stages 430 can supply power to the DC bus 510 of that stagethrough the synchronous common coupling 440.

In further embodiments, the source/load bridge 432 is designed toprovide a bypass of the stage 430 in the case of a failed powercomponent or some control failures. If the source/load bridge 432 failsto operate properly, the source/load bridge 432 is designed tonaturally, or through positive control, deliberately turn on the powerdevices within the source/load bridge 432 continuously to short out thepower input to stage 430. In cases, where the stages 430 are connectedin parallel, a means of disconnecting the failed stage 430 from otherparallel healthy stages 430 may be provided, such as a fuse, contact,semiconductor, and/or the like. According to some embodiments, theswitching devices of the source/load bridge 432 and the flux bridge 434may have overcurrent sensing for protection.

Further, the source/load bridge 432 is controlled by a stage controller550 to regulate current, DC bus voltage, and the power for the stage430, stack 420, and array 410 to specified values. The source/loadbridge 432 semiconductors 530A-D may be switched at high or lowfrequencies or a combination of both depending on the control strategyto regulate the network current. When high-frequency (>10 KHz) switchingstrategy is used, then fast silicon IGBTs or metal-oxide-semiconductorfield-effect transistors (“MOSFETs”) or Wide Band Gap MOSFETs may beused depending on required cost, efficiency, and ratings. When lowfrequency switching (<1 KHz) is used, then low forward saturationsilicon IGBTs are possible as well as IGBT and IGCT modules.

Similarly to the source/load bridge 432, the flux bridge 434 maycomprise two, four or any other number of switching devices (IGBT, IGCT,WBG, etc.) in a half, full or other suitable topology bridgeconfiguration. For example, the flux bridge 434 may comprise fourswitches devices 540A-D comprising IGBTs configured in a conventionalH-bridge configuration, as shown in FIG. 5. The flux bridge 434 mayoperate on a simple symmetrical duty cycle. The actual operatingfrequency may be determined by the type of device used.

The flux bridge 434 output may connect to an electrically isolatedwinding 436 located on high-frequency transformer core (for example 25kHz to 250 kHz) in the synchronous common coupling 440. If more than onestage 430 is used, the electrical winding 436 may be located on a commonhigh-frequency transformer core. According to embodiments, the stagecontroller 550 for each flux bridge 434 circuit is synchronized so thatpower to the windings 436 of each stage 430 are in phase and at the samefrequency. The power through the flux bridge 434 may be bi-directional.If so, the bridge rectifies the voltage and passes power to the DC bus510 which is regulated by the source/load bridge 432. The switchingdevices 540A-D of the flux bridge 434 are switched synchronously withother flux bridges 434 of other stages 430 within each array 410 athigh-frequency (e.g., >10 KHz) to reduce the size of the single commonflux core 450 (or cores 602) and the number of turns in the winding 436of the synchronous common coupling 440, as is further described herein.

In some embodiments, the flux bridge 434 may be soft-switched through aresonant capacitor 514 and/or inductor 512 connected in series with thewindings 436. In other embodiments, the flux bridge 434 may be may behard switched, without the use of the resonant capacitor 514 andinductor 512. In some embodiments, the flux bridges 434 of one or morestages 430 may temporarily change switching frequency to enable betterpower flow. In some embodiments, the current to the winding 436 may bemonitored with a current shunt or an isolated current sensor by thestage controller 550.

The stage controller 550 may control the switching devices 530A-D and540A-D of the source/load bridge 432 and flux bridge 434 by switchingthem on and off utilizing PWM switching. The stage controller 550 mayutilize an average current mode controlled power factor correctionalgorithm or the like. The stage controller 550 may comprise a DC-DCpower supply powered by a wireless power supply which has a transmitterin the cell and a receiver (not shown) on the stage 430, a DC-DCconverter that receives its power from the DC bus 510, or other powermeans. The power supply for the stage 430 may receive back-up power fromcontrol power of an adjacent stage when more than one stage 430 exists.

In some embodiments, the DC bus 510 may comprise DC bus capacitors 508,a voltage feedback circuit 506, and a DC-DC power supply. The voltage ofthe DC bus 510 may be regulated by the source/load bridge 432 via thestage controller 550, and may be measured via a power resistor dividernetwork. In some embodiments, the power management system may beimplemented with digital isolation circuits 560 that have high noiseimmunity that may provide fast digital control from each stage 430 to aparticular stage within a stack 420.

According to some embodiments, the stage controller 550 may beimplemented to direct the source/load bridge 432 to control the ACcurrent. According to some embodiments, the stage controller 550 maycomprise shunt resistors to measure the current. In some embodiments,the AC/DC input voltage may be measured at each stack 420, at each stage430, or at the stage controller 550. In some embodiments, if theincoming voltage is AC, the phase angle and a synchronized signalrepresenting the zero crossing(s) may be communicated throughout thepower management system 400. In some embodiments, the stage controller550 may comprise feedback sensors to detect temperature near the stage430, the stage controller 550, the DC bus capacitor 508, and/or thetransformer winding 436.

Referring again to FIG. 4, according to some embodiments, the powermanagement system 400 may be implemented with a minimum of two ports 406with the maximum number being unlimited. In the example 6-port systemshown in FIG. 4, there are 6 ports 406A-F (also referred to hereingenerally as ports 406). In the example embodiment, each port 406A-F isa bidirectional power port and may be connected to a power source or aload, as shown at 402A-F. In some embodiments, the current harmonics maybe minimized by means of a current regulating reactor 404 locatedbetween the port 406A-F and the corresponding source/load connection402A-F. The current regulating reactor 404 may also provide protectionfrom lightning or large fast network voltage transients.

According to some embodiments, the power management system 400 may bebidirectional through ports 406 such that the array is indifferent towhether a source or a load connection 402 is connected at each port 406.As shown in FIG. 4, the power management system 400 may comprise of onearray 410, with three stages 430 in each of six stacks 420A-F. A stack420 may comprise one or more stages 430 connected in a series connectionstring 422, according to some embodiments. An array 410 may comprise agroup of two or more stacks 420 combined with a synchronous commoncoupling 440. According to some embodiments, an array 410 may beconnected in series and/or parallel with other arrays.

According to some embodiments, a stack 420 may be configured to controlpower bi-directionally at its configured input, which may also be anarray port 406, from the corresponding source/load connection 402.According to some embodiments, if one stage 430 fails, the stack 420 mayattempt to short its input by permitting the voltage to rise across theinput enough for the semiconductors to fail shorted and the rest of thearray 410 continues to operate through redundant stages 430A-N withinthe series circuit, or stack 420. If the internal failure occurs in suchway that the whole or much more of the array 410 is damaged, then otherredundancy measures are available such as configured parallel arrays410. Each stage 430 is provided with a means of synchronous commoncoupling 440 to other stage 430 to better control power, whilemaintaining electrical isolation between stages 430. The cascadedmulti-level and multi-port power management system 400 may operate inVAR compensation configuration, also referred to herein as a “shunt,” orin a power conversion configuration, also referred to here as “series”or “transformer” configuration, within the electrical network dependingon application.

In some embodiments, the synchronous common coupling 440 utilizes asingle common flux core 450 to exchange power directly betweenelectrically isolated and non-isolated stages 430A-N of the stacks420A-F, as shown in the example embodiment of the cascaded multi-leveland multi-port power management system 400 in FIG. 4. The path of thepower for this example embodiment would be: AC1-DC-COMMON FLUX CORE 450.In other words, within each stage 430, a port 406 (connected tosource/load connection 402) is connected to the source/load bridge 432(which is referred to here as AC1) and input power is converted to“regulated DC voltage.” The regulated DC voltage is synchronized to thesynchronous common coupling 440 by the flux bridge 434 and connectedthrough the winding 436 to the common flux core 450, which links thepower to other stages 430A-N in the system. There are multiple windings436 wound on the single common flux core 450, with each windingconnected to a stage 430, which creates the synchronous common coupling440. According to some embodiments, each array 410 in the powermanagement system 410 may have its own synchronous common coupling 440,such as the common flux core 450 shown in FIG. 4. In other embodiments,the power management system 410 may comprise multiple arrays 410, eachhaving separate synchronous common couplings 440 or multiple arrayssharing a same synchronous common coupling.

In power management systems 400 utilizing a single common flux core 450,high-frequency flux travels within the core 450 to other windings 436distributed on the single common flux core 450. For resonant operation,the synchronous common coupling 440 behaves best for lowest leakage fluxvalues and smallest leakage variation in the single common flux core450. In some embodiments, an external inductor may be used inhigh-frequency power supply circuits to minimize the effects of leakagevariation. In some embodiments hard switching the flux bridge 434 andwindings 436 may be used.

FIG. 6 is a block diagram illustrating a cascaded multi-level andmulti-port power management system 600 with the synchronous commoncoupling 440 comprising multiple high-frequency transformers to create ahigh-frequency current bus 620, according to some embodiments describedherein. As shown in FIG. 6, an exemplary cascaded multi-level andmulti-port power management system 600 may comprise six ports 406A-Fwith one array 410. According to some embodiments, the power managementsystem 600 may be implemented with one transformer 602 per stage 430. Insome embodiments, multiple stages 430A-N may utilize a singletransformer 602 with a single core and separate windings for each stage,combining the features of both the single common flux core 450 and thehigh-frequency current bus 620.

For example, the cascaded multi-level and multi-port power managementsystem 600 may be implemented in which the synchronous common coupling440 utilizes multiple cores that exchange power directly betweensecondary windings connected together through the high-frequency currentbus 602 and powered by electrically isolated stages 430A-N. The path forpower in this example embodiment would be: AC1-DC-XFMR-COMMON FLUXCOUPLING. In other words, within each stage 430, a port 406 (connectedto a source/load connection 402) is connected to the source/load bridge432 (which is referred to here as AC1) and input power is converted to“regulated DC voltage.” The regulated DC voltage is synchronized to thesynchronized common coupling 440 through the flux bridge 434 andconnected to a transformer 602 with at least one primary winding 436. Asecondary winding 604 of the transformer 602 transfers the power to allstages 430 in the array 610 through the high-frequency current bus 620,as shown in FIG. 6. According to some embodiments, the cascadedmulti-level and multi-port power management system 600 may beimplemented with the high-frequency current bus 620 utilizing selectionand switching frequency to minimize leakage inductance and meetefficiency requirements.

According to some embodiments, multiple core systems may be implementedwith a high-frequency current bus 620 flowing from primary winding 436to secondary windings 604 through the core 602 to other stages 430A-Nvia the secondary windings 604 which are connected in parallel withinthe array 610. For resonant operation, the synchronous common coupling440 behaves best for lowest leakage flux values and smallest leakagevariation in the core 602. In some embodiments, an external inductor maybe used in high-frequency power supply circuits to minimize effects ofleakage variation. In some embodiments, hard switching the flux bridge434 and windings 436 may be used.

FIG. 7 depicts a block diagram illustrating a multi-level and multi-portcascaded power management system 700 with synchronous common coupling440 and a 3-port array 710 in a “coin” configuration, according to someembodiments described herein. According to some embodiments, themulti-level and multi-port cascaded power management system 700 may beimplemented with one array 710 connected to a three-phase AC powernetwork to act as a VAR compensator or “shunt regulator.” In otherembodiments, this configuration may be utilized for line balancing,transformer impedance matching, or the like.

As shown in FIG. 7, an exemplary array 710 may comprise three stacks420A-C, where each stack 420 comprises of multiple stages 430A-N, andeach stack 420 is connected in series. In other embodiments, the numberof stages 430, stacks 420, and arrays 710 used to form a powermanagement system may depend on the network operating voltage and power.According to further embodiments, in a multi-level cascade converter,each stage 430 may contribute to the voltage and power on a single-phasebasis, where the actual voltage and power rating of the array 710depends on the number of stages 430A-N used and at what power andvoltage each one is utilized. According to some embodiments, the voltageof the multi-level and multi-port cascaded power management system 700may be normally distributed evenly, whereas the power contribution mayalso be the same or vary.

FIGS. 8 and 9 are block diagrams illustrating typical cascadedmulti-level and multi-port power management systems 800 and 900 withsynchronous common coupling 440, according to some embodiments describedherein. FIG. 8 illustrates a cascaded multi-level and multi-port powermanagement system 800 with synchronous common coupling 440 in a shuntapplication used for VAR compensation and line balancing, according tosome embodiments described herein. FIG. 9 illustrates a cascadedmulti-level and multi-port power management system 900 with synchronouscommon coupling 440 in a series application to provide power flowcontrol, according to some embodiments described herein. According tosome embodiments, each cascaded multi-level and multi-port powermanagement system 800, 900 may be implemented with a 3-port systemcomprising one or more power module ports 802A-C with multiple arrays830A-N in a series configuration. According to some embodiments, thepower module 810 may be implemented with one or more arrays 830A-N, oneor more current regulating reactors 404, and a high-frequency pre-chargeand power supply assembly 860. In some embodiments, each cascadedmulti-level and multi-port power management system 800, 900 may includenetwork voltage and current feedback 840 and may comprise an enclosurewith grounding provisions.

As shown in FIGS. 8 and 9, a multi-level and multi-port cascaded powermanagement system 800, 900 may further comprise a central controller850. According to some embodiments, the central controller 850 maycoordinate operations of each stage 430, stack 420, and array 410 withinthe system to meet the network requirements. According to someembodiments, the central controller 850 may use average current modecontrolled power factor correction algorithms, or the like. In someembodiments, numerous sources and loads may be connected within thepower management system 800, 900, and there may be several powermanagement systems operating with independent control, but workingtogether as one large power management system which may be controlled bythe central controller 850 to control power flow within the electricalnetwork. In some embodiments, the central controller 850 is incommunication with an energy network and may request to receive energyfrom the energy network. According to some embodiments, the centralcontroller 850 may be configured to process and analyze the externalnetwork energy needs by either receiving requests from another entity,or determining requirements through evaluating current and voltagefeedback magnitude, power factor, phase angle, harmonic content,sequence, frequency and other such characteristics feedback providedfrom the power flow within the external network.

FIG. 10 is a block diagram illustrating a cascaded multi-level andmulti-port power management system 1000 with a high-frequency pre-chargeand power supply assembly 860 connected to a power module 1010 withmultiple stacks 420A-N comprising multiple stages 430A-N, according tosome embodiments described herein. According to some embodiments, thehigh-frequency pre-charge and power supply assembly 860 may providepower to each stage 430A-N, stack 420A-N, array 410A-N, power module1010, and the cascaded multi-level and multi-port power managementsystem 1000 from a low voltage power source 1060 to fully test theassembly prior to applying high power. According to some embodiments,the high-frequency pre-charge and power supply assembly 860 may beimplemented by connecting a low voltage source (e.g. battery orauxiliary power) to supply charging current and stage control power toeach stage 430 within an array 410A-N.

According to some embodiments, the high-frequency pre-charge and powersupply assembly 860 provides electrically isolated charging current toat least one DC bus 510 of one stage 430 within a stack 420A-N, andpower is distributed within the array 410 by the synchronous commoncoupling 440 to prevent inrush current to the DC bus 510 when high poweris connected. According to some embodiments, the pre-charge circuitry1032 may be implemented to maintain the proper voltage in the stages 430during an outage indefinitely if power is lost on one or more sources,so that they are prepared to return to proper function immediately uponrestoration of power.

According the some embodiments, the high-frequency pre-charge and powersupply assembly 860 may be implemented with a high voltage cable poweredby a secondary of the high-frequency current source switching regulator1050 with an isolation transformer 1042 to provide high-frequencycurrent to a high voltage conductor 1046 that shunts the transformersecondary 1044. According to some embodiments, the high voltageconductor 1046 may serve as the primary winding 1002 to the cores 1004with multi-winding secondaries mounted on each stack 420A-N. Further,the primary windings 1002 and cores 1004 may provide isolated power tothe stage controller 550 within each stage 430A-N and pre-charge thepre-charge circuitry 1032 of at least one DC bus 510 of a stage 430within each stack 420A-N. The synchronous common coupling 440 maydistribute and balance DC bus power throughout each stage 430. Accordingto some embodiments, at least one DC bus 510 of each stage 430 may beconnected to the pre-charge circuitry 1032 such that all DC buses may becharged through the one stage 430 by the synchronous common coupling440.

In some embodiments, the cascaded multi-level and multi-port powermanagement system 1000 may supply balanced or unbalanced power to anyport via the high-frequency pre-charge and power supply assembly 860.According to some embodiments, the system may comprise the addition ofstorage to give more flexibility in speed of response, which may emulatethe inertia of synchronous machines. The higher the power, the moreunbalance and regulation assistance the auxiliary, pre-charge, and acontrol port may provide. In some embodiments, the cascaded multi-leveland multi-port power management system 1000 may reduce repair timebecause stages 430A-N, stacks 420A-N, arrays 410A-N, power modules 1010,and entire power management system assemblies can be tested anywhere bypowering the pre-charge circuitry 1032 and high-frequency pre-charge andpower supply assembly 860 with low voltage power from the low voltagepower source 1060.

FIG. 11 is a block diagram illustrating a stage circuit assembly 1100for a stage 430 comprising one source/load bridge 432 connected tomultiple flux bridges 434A-434N through corresponding DC busses510A-510N, according to some embodiments. Each of the DC busses510A-510N may include a DC bus capacitor 508 across the correspondingflux bridge 434A-434N. Each flux bridge 434A-434N may be furtherconnected to the synchronous common coupling 440 through a separatewinding 436. The multiple DC buses 510A-510N, each regulated through thecorresponding winding 436 on the synchronous common coupling 440,effectively create a single, higher voltage, regulated DC bus for thesingle source/load bridge 432. According to this embodiment, allwindings 436 in the synchronous common coupling 440 may not beelectrically isolated, as will be appreciated by one skilled in the artfrom the block diagram of FIG. 11.

The use of multiple flux bridges 434A-434N with a single source bridge432 in a stage 430 may provide for the use of resonant-type bridging inthe flux bridges, and allow the use of lower voltage, higher frequencyswitches and other, less expensive components. Further, the presence ofthe synchronous common coupling 440 with multiple flux bridges 434A-434Nwithin a stage 430 automatically keeps the voltage across eachcorresponding DC bus capacitor 508 in balance, allowing for smaller andcheaper capacitors to be utilized, requiring less engineering designcost to balance the capacitors and simpler control logic.

The circuitry and/or logic of the stage controller 550 may be adjustedto accommodate the multiple flux bridges 434A-434N connected to the samesynchronous common coupling 440 within the stage 430. It will be furtherappreciated that the input filter 520, stage controller 550 and digitalisolation circuits 560 described above in regard to FIG. 5 may bepresent in the stage circuit assembly 1100 shown in FIG. 11, and areonly omitted here for clarity. Similarly, the flux bridges 434A-434N ofthe stage circuit assembly 1100 may be soft-switched through a resonantcapacitor 514 and/or inductor 512 connected in series with thecorresponding windings 436, as further described in regard to FIG. 5.

It will be appreciated that any number of source/load bridges 432 andflux bridges 434 may be present in a stage 430 or divided among multiplestages. For example, FIG. 12 is a block diagram illustrating anotherexample of a stage circuit assembly 1200 for a stage 430 comprising somenumber K of source/load bridges 432A-432K connected to some number N offlux bridges 434A-434N through corresponding DC busses 510A-510N. Thespecific embodiments shown in the figures and described herein are notmeant to be limiting, and it is intended that all combinations of sourcebridges and flux bridges connected to a synchronous common coupling beincluded in this disclosure.

In addition, a stage 430 may contain no source/load bridges, as furthershown in FIG. 13. FIG. 13 shows a stage circuit assembly 1300 for astage 430 comprising multiple flux bridges 434A-434N connected to a DCsource/load 402 through corresponding DC busses 510A-510N. The DCsource/load 402 may drive the voltage in the DC busses 510A-510Ndirectly without the need for source/load bridge(s) 432, according tofurther embodiments. A power management system may implement the stagecircuit assembly 1300 in its stages 430 when a high-voltage DC source isutilized to drive one or more multiphase AC loads, for example.

FIG. 14 shows a power management system 1400 comprising high-frequency,multiphase outputs 1402A-1402C, according to further embodiments. Thepower management system may comprise a number of arrays 410A-410C, eacharray associated with one phase of the multiphase outputs 1402A-1402C.Each of the arrays 410-410C may comprise one or more stacks 420A-420J.In some embodiments, the number of stacks 420 in each of the arrays410A-410C may correspond to the number of phases of the source power,such as three stacks for each array corresponding to three source powerphase 402A-402C, as shown in FIG. 14. Each stack 420 may comprise anynumber of cascaded stages 430, with each stage having any number ofsource/load bridges 432 and flux bridges 434, according to the variousembodiments described herein.

The stacks 420 of each array 410A-410C may be further connected towindings 436A-426J of a synchronous common coupling 440A-440C for thearray. The high-frequency, multiphase output 1402A-1402C associated witheach array 410A-410C may also be directly connected to the synchronouscommon coupling 440A-440C of the array by a winding 144A-1404C.According to embodiments, the multiphase power management system 1400shown in FIG. 14 may be utilized to supply power to high-frequency,industrial motors. For example, the multiphase power management system1400 may be configured to provide three phase power output at 1 KHz orgreater from a standard three-phase, 60 Hz power source. The use ofhigh-frequency output may allow for the use of smaller, less expensivemotors to achieve a given speed and/or torque requirement, as is knownin the art.

It will be appreciated that cascaded multi-level and multi-port powermanagement systems 400, 600, 700, 800, 900, 1000, and 1400 and powermodules 810, 1010 may comprise any number of arrays 410, the arrays maycomprise any number of stacks 420, the stacks may comprise any number ofstages 430, and each system or component may comprise any number ofports, and they may be combined in various ways for variousconfigurations of a power management system, according to theembodiments described herein. In addition, each stage 430 may containany number of source/load bridges 432 and/or flux bridges 434 dependingon the requirements of the implemented multi-port power managementsystem.

Other aspects can comprise additional options or can omit certainoptions shown herein. One should note that conditional language, suchas, among others, “can,” “could,” “might,” or “may,” unless specificallystated otherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain aspects comprise, while otheraspects do not comprise, certain features, elements and/or steps. Thus,such conditional language is not generally intended to imply thatfeatures, elements and/or steps are in any way required for one or moreparticular aspects or that one or more particular aspects necessarilycomprise logic for deciding, with or without user input or prompting,whether these features, elements and/or steps are comprised or are to beperformed in any particular aspect.

The description is provided as an enabling teaching of the presentdevices, systems, and/or methods in their best, currently known aspects.To this end, those skilled in the relevant art will recognize andappreciate that many changes can be made to the various aspectsdescribed herein, while still obtaining the beneficial results of thepresent disclosure. It will also be apparent that some of the desiredbenefits of the present disclosure can be obtained by selecting some ofthe features of the present disclosure without utilizing other features.Accordingly, those who work in the art will recognize that manymodifications and adaptations to the present disclosure are possible andcan even be desirable in certain circumstances and are a part of thepresent disclosure. Thus, the description is provided as illustrative ofthe principles of the present disclosure and not in limitation thereof.

As used throughout, the singular forms “a,” “an” and “the” compriseplural referents unless the context clearly dictates otherwise. Thus,for example, reference to a quantity of one of a particular element cancomprise two or more such elements unless the context indicatesotherwise. As used herein, the terms “optional” or “optionally” meanthat the subsequently described event or circumstance may or may notoccur, and that the description comprises instances where said event orcircumstance occurs and instances where it does not.

It should be emphasized that the above-described examples are merelypossible examples of implementations and set forth for a clearunderstanding of the present disclosure. Many variations andmodifications can be made to the above-described examples withoutdeparting substantially from the spirit and principles of the presentdisclosure. Further, the scope of the present disclosure is intended tocover any and all appropriate combinations and sub-combinations of allelements, features, and aspects discussed above. All such appropriatemodifications and variations are intended to be comprised within thescope of the present disclosure, and all possible claims to individualaspects or combinations of elements or steps are intended to besupported by the present disclosure.

What is claimed is:
 1. A power management apparatus utilizing synchronous common coupling, the power management apparatus comprising: a synchronous common coupling; a plurality of ports; and a plurality of stacks connected through the synchronous common coupling, each stack comprising at least one stage, each stage comprising at least one source/load bridge, at least one flux bridge, and a DC bus; wherein the at least one source/load bridge of one stage of each stack is connected to a source or load through one of the plurality of ports, the at least one flux bridge of each stage is connected to an electrically isolated winding in the synchronous common coupling, and the at least one flux bridge of each stage is connected to the at least one source/load bridge of the stage through the DC bus, the synchronous common coupling configured to exchange power between each of the plurality of stacks.
 2. The apparatus of claim 1, wherein the at least one stage comprises one source/load bridge and a plurality of flux bridges, each of the plurality of flux bridges further connected across a corresponding DC bus capacitor on the DC bus.
 3. The apparatus of claim 1, wherein the at least one stage comprises a plurality of source/load bridges and a plurality of flux bridges, the number of source/load bridges and the number of flux bridges being different.
 4. The apparatus of claim 1, wherein the synchronous common coupling comprises a single common flux core, and wherein the at least one flux bridge of each stage is connected to an electrically isolated winding on the single common flux core.
 5. The apparatus of claim 1, wherein the synchronous common coupling comprises a high-frequency current bus, and wherein the at least one flux bridge of each stage is connected to the high-frequency current bus through a separate transformer.
 6. The apparatus of claim 1, wherein the at least one stage of each of the stacks further comprises control circuitry to control the transmission of power through the stage.
 7. The apparatus of claim 6, wherein the control circuitry of each stage is configured to switch the flux bridge of the stage in a synchronized fashion so that power to the connected electrically isolated winding in the synchronous common coupling is in phase and at a same frequency.
 8. The apparatus of claim 6, wherein one of the plurality stacks is connected through the port associated with the stack to a power source and another of the plurality stacks is connected through the the port associated with the stack to a load, and the control circuitry is configured to operate the apparatus for power conversion.
 9. The apparatus of claim 6, wherein one of the plurality stacks is connected through the port associated with the stack to a first phase of a multiphase AC power source and another of the plurality stacks is connected through the the port associated with the stack to a second phase of the multiphase AC power source, and the control circuitry is configured to operate the apparatus for VAR compensation.
 10. The apparatus of claim 6 further comprising a central controller configured to control the control circuitry on each stage.
 11. A power management system utilizing synchronous common coupling, the power management system comprising: a plurality of source/load ports; a stack connected to each source/load port, each stack comprising at least one stage, the at least one stage comprising a DC bus, at least one flux bridge, and a stage controller, the at least one flux bridge connected to an electrically isolated winding in the synchronous common coupling, the stage controller configured to switch the at least one flux bridge in a synchronized fashion so that power flows from the DC bus of each stack to the connected electrically isolated winding in the synchronous common coupling in phase and at a same frequency, the synchronous common coupling configured to exchange power between the stacks; and a central controller configured to control and synchronize each stage controller.
 12. The power management system of claim 11, wherein the DC bus of the at least one stage is connected directly to the source/load port of the stack.
 13. The power management system of claim 11, wherein the at least one stage further comprises at least one source/load bridge between the DC bus and the connected source/load port, and the stage controller is further configured to switch the at least one source/load bridge to convert AC power at the source/load port to DC power on the DC bus.
 14. The power management system of claim 11, wherein the at least one stage comprises a plurality of flux bridges, each of the plurality of flux bridges further connected across a corresponding DC bus capacitor on the DC bus.
 15. The power management system of claim 11, wherein the stack comprises a plurality of stages connected in a cascaded fashion.
 16. The power management system of claim 11, wherein the synchronous common coupling comprises a single common flux core, and wherein the at least one flux bridge of each stage is connected to an electrically isolated winding on the single common flux core.
 17. The power management system of claim 11, further comprising a plurality of arrays, each array comprising a plurality of source/load ports and an isolated synchronous common coupling, each of the plurality of source/load ports connecting a stack of the array to one phase of a multiphase AC power source, the isolated synchronous common coupling of each array further comprising a winding connected to one phase of a high-frequency, multi-phase output.
 18. A method of utilizing synchronous common coupling for power management, the method comprising the steps of: connecting a power source to a first source/load port of a power management system, the power management system comprising a plurality of stacks, a first stack of the plurality of stacks connected to the first source/load and comprising at least one stage, the at least one stage comprising at least one source/load bridge, a DC bus, at least one flux bridge, and control circuitry, the at least one source/load bridge connected between the first source/load port and the DC bus, and the at least one flux bridge of the stage is connected between the DC bus and an electrically isolated winding of the synchronous common coupling; and controlling, by the control circuitry, a flow of power between the first source/load port and the synchronous common coupling by switching the at least one source/load bridge to synchronize power between the first source/load port and the DC bus and switching the at least one flux bridge to synchronize power between the DC bus and the electrically isolated winding of the synchronous common coupling, the synchronous common coupling configured to exchange power between the plurality of stacks.
 19. The method of claim 18, further comprising the steps of: connecting a second source/load port of the power management system to a load, the second source/load port connected to a second stack of the plurality of stacks; and controlling the control circuitry of the first stack and the second stack such that the power management system converts power from the power source connected to the first source/load port to power required by the load connected to the second source/load port.
 20. The method of claim 18, wherein the first source/load port is connected to a first phase of the power source, the method further comprising the steps of: connecting a second source/load port of the power management system to a second phase of the power source, the second source/load port connected to a second stack of the plurality of stacks; and controlling the control circuitry of the first stack and the second stack such that the power management system provides VAR compensation between the first phase and the second phase of the power source. 